Regensburg 2025 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 37: Correlated Electrons: Poster

TT 37.57: Poster

Wednesday, March 19, 2025, 15:00–18:00, P4

Two site entanglement in the two dimensional Hubbard model — Anna Kauch¹, •Gergo Roosz², Frederic Bippus¹, Daniel Wieser¹, Fakher Assaad^3,4, and Karsten Held¹ — ¹Institute of Solid State Physics, TU Wien, 1040 Vienna, Austria — ²HUN-REN Wigner RCP, Budapest — ³Universitat Wurzburg, 97074 Wurzburg, Germany — ⁴Wurzburg-Dresden Cluster of Excellence ct.qmat, Am Hubland, 97074 Wurzburg, Germany

We calculate the reduced density matrix of two sites in the two-dimensional Hubbard model using the D Gamma A method. We calculate the density matrix by calculating the expectation value of a complete set of hermitian operators in the subspace of the two sites. We can express these eigenvalues with the one- and two-particle Greens functions, and the imaginary time derivatives of these functions. The derivatives are calculated in Matsubara representation. To test convergence we compare our results for the second Renyi entropy with quantum Monte Carlo data. To investigate the entanglement and correlations of the Hubbard model we calculate the mutual information and the entanglement negativity between the two sites.

Keywords: Hubbard model; dynamical vertex approximation; quantum Monte-Carlo; entanglement; mutual information